docs: def get_all_lexers():
      """Return a generator of tuples in the form ``(name, aliases,
      filenames, mimetypes)`` of all know lexers.
      """
      for item in itervalues(LEXERS):
          yield item[1:]
      for lexer in find_plugin_lexers():
          yield lexer.name, lexer.aliases, lexer.filenames, lexer.mimetypes